Airbag module cover

ABSTRACT

A cover for an airbag module includes at least a first layer, a second layer, and a third layer. The first layer includes a predefined tear line and the third layer is configured to face into a passenger compartment of a vehicle.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Divisional of U.S. application Ser. No.10/944,773, filed Sep. 21, 2004.

BACKGROUND OF THE INVENTION

The present invention relates to an airbag module and, moreparticularly, to an airbag module cover that includes an outer surfacethat forms part of a vehicle instrument panel.

In an airbag device for a vehicle, an airbag is typically accommodatedin an airbag module that includes a retainer covered by a module cover.The retainer is connected to the vehicle structure, and the outersurface of the module cover faces into the vehicle passengercompartment. For a driver airbag device, the airbag module is mounted toa steering wheel of a vehicle. For a passenger airbag device, the airbagmodule is mounted to an instrument panel of the vehicle. In the event ofa vehicle emergency such as a collision, an inflator in the airbagmodule delivers inflation gas into the airbag thereby inflating theairbag. As the airbag inflates, the airbag exerts pressure on the modulecover. When sufficient pressure is exerted on the module cover, thecover ruptures and opens toward the inside of the vehicle cabin therebyallowing the airbag to be inflated inside the vehicle cabin to protect avehicle occupant.

One disadvantage of conventional airbag modules is that the module covermust be made of materials that can be configured to rupture and that canwithstand high airbag deployment temperatures. As a result, conventionalmodule covers typically include an injection molded base layer having apre-weakened portion such as a tear line groove that ruptures or breakswhen sufficient pressure is exerted on the module cover by the inflatingairbag. Conventional module covers generally also include a surfacesheet disposed on the base layer so that the outer surface of the modulecover matches the appearance and feel of the vehicle instrument panel.The surface sheet may include a lower layer formed of a thermallyresistant resin, a middle layer formed of a soft foamed resin, and anouter decorative layer formed of a thermoplastic elastomer (TPE). TheTPE can be, for example, polyolefin based (TPO), polystyrene based(TPS), polyvinyl chloride based, polyester based, polyamide based, orurethane based.

As a result of the above requirements and construction, the design andappearance (e.g., texture, color, pattern, surface finish) ofconventional module covers is limited. Moreover, the thermoplasticelastomers forming the decorative layer are not well suited forapplication of coatings and paints thereby further limiting theappearance of the module cover so that desired customer finishes oftencan not be achieved.

SUMMARY OF THE INVENTION

According to one embodiment of the present invention, cover for anairbag module is provided. The cover includes at least a first layer, asecond layer, and a third layer. The first layer includes a predefinedtear line and the third layer is configured to face into a passengercompartment of a vehicle.

According to another embodiment of the present invention, a cover for anairbag module includes a base layer and a substrate disposed on the baselayer. The substrate includes a pair of panels each including an outerlayer.

According to another embodiment of the invention, an airbag module for avehicle includes an airbag, an inflator, and a cover. The cover includesa top surface facing toward an interior of the vehicle. The top surfacecomprises metal.

According to another embodiment of the invention, an airbag module isconfigured to be positioned in a vehicle so that a cover of the moduleforms a portion of the vehicle instrument panel. The cover includes ametal top layer configured to separate into at least two pieces to allowan airbag to deploy therethrough.

According to yet another embodiment of the invention, a method offorming a cover for an airbag module includes providing a base layerhaving a pre-weakened portion for deploying an airbag, providing asubstrate having a first panel and a second panel, providing a firstmetal sheet and a second metal sheet, wrapping the first metal sheetaround the first panel so that the first metal sheet substantiallycovers front and side surfaces of the first panel, wrapping the secondmetal sheet around the second panel so that the second metal sheetsubstantially covers front and side surfaces of the second panel, andattaching the first and second panels to the base layer.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory only,and are not restrictive of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate a preferred embodiment of theinvention and together with the description, serve to explain principlesof the invention.

FIG. 1 is a cross sectional side view of an embodiment of an airbagmodule according to the present invention.

FIG. 2 is a top plan view of a module cover of the airbag module of FIG.1.

FIG. 3A is a perspective view of a substrate and a surface layer of themodule cover of FIG. 2 showing the surface layer prior to installationon the substrate.

FIG. 3B is a cross sectional view taken along the line A-A of FIG. 3Ashowing the surface layer installed on the substrate.

FIG. 3C is a cross sectional view taken along the line B-B of FIG. 3Ashowing the surface layer installed on the substrate.

FIG. 4 is a perspective view of the airbag module of FIG. 1 installed ina vehicle instrument panel.

FIG. 5 is a cross sectional side view of an embodiment of an airbagmodule according to the present invention.

FIG. 6 is a cross sectional side view of a cover layer of FIG. 5.

FIG. 7 is a cross sectional side view according to an embodiment of thepresent invention showing attachment of an airbag module cover layer toa base layer.

FIG. 8 is a cross sectional side view of an embodiment of an airbagmodule according to the present invention.

DETAILED DESCRIPTION

FIGS. 1-4 show an embodiment of an airbag module 100 according to thepresent invention. The airbag module 100 includes an airbag 10, aninflator 20, a retainer 30, and a module cover 40.

The airbag 10, the inflator 20, and the retainer 30 are not specific tothe present invention and may be any airbag, inflator, and/or retainergenerally known to those of skill in the art. Similarly, the airbag 10,the inflator 20, the retainer 30, and the module cover 40 may beconnected together and installed in a vehicle using known methods andcomponents. For example, the retainer 30 may be configured to beconnected to the vehicle structure. The airbag 10 and the inflator 20may be secured to the retainer 30. The retainer 30 and the module cover40 may be connected together so that an enclosure 35 is formed betweenthe retainer 30 and the module cover 40. The airbag 10 is disposed inthe enclosure 35 in a folded state (shown in FIG. 1) and is operativelyconnected to the inflator 20. During a vehicle emergency, the inflator20 generates inflation gas, which flows into the airbag 10 to inflatethe airbag 10.

According to an embodiment, the module cover 40 includes a skirt 42 anda lid 44. The skirt 42 projects from a rear (or inner) surface of thelid 44 as shown in FIG. 1. As is well known, the skirt 42 may be, forexample, a continuous member or may include a plurality of separate legmembers. The skirt 42 provides an interface for connecting the modulecover 40 to the retainer 30. For example, the skirt 42 may be connectedto a corresponding connector portion 32 of the retainer 30 in any mannerknown to those of skill in the art.

The lid 44 of the module cover 40 forms part of a vehicle instrumentpanel 200 when the airbag module 100 is installed in a vehicle. As shownin FIG. 5, a front (or outer) surface of the lid 44 is substantiallyaligned with an outer surface 270 of the instrument panel 200 and facestoward an interior 300 of the vehicle (i.e., into a vehicle passengercompartment). The lid 44 includes a base layer 50 and a cover layer 60.The base layer 50 underlies the cover layer 60 and forms the rearsurface of the lid 44. The cover layer 60 is attached to the base layer50 and forms the front surface of the lid 44 as shown in FIG. 1.

The cover layer 60 may be attached to the base layer 50 using attachmenthardware or an adhesive. The cover layer 60 may also be configured tosnap onto the base layer 50. In an exemplary embodiment, the base layer50 includes a plurality of through holes, and the cover layer 60includes corresponding bosses B. The cover layer 60 is connected to thebase layer 50 by inserting the bosses B into the through holes andpost-forming (e.g., melting) the bosses B to retain the cover layer 60on the base layer 50 as shown in FIG. 7. In another exemplaryembodiment, the cover layer 60 is secured to the base layer 50 by tabsT. As shown in FIG. 6, the tabs T are disposed on a bracket 67 (e.g., astamped metal bracket). The bracket 67 may be inserted into recesses(not shown) in the substrate 65 or molded into the substrate 65 so thatthe tabs T project from the substrate 65. The base layer 50 includescorresponding through holes into which the tabs T are inserted. As shownin FIG. 5, the tabs T are then bent over to mechanically secure thecover layer 65 to the base layer 50. The bent tabs T may be heat stakedfor additional strength.

The base layer 50 of the lid 44 may be made of any plastic or polymersuitable for use in an airbag module cover application. However, thebase layer 50 is preferably formed of thermoplastic olefin (TPO).Additionally, a groove 52 (shown in FIG. 1) may be formed in the baselayer 50. The groove 52 is a pre-weakened tear line (or breaking point)that ruptures when the inflating airbag 10 exerts sufficient pressure onthe lid 44. When the airbag 10 inflates, the groove 52 ruptures and thelid 44 swings open at the groove 52 to enable the inflating airbag 10 todeploy through the lid 44 into the vehicle passenger compartment 300.

The cover layer 60 of the lid 44 includes a substrate 65 and a surfacelayer 70.

The substrate 65 forms the structure of the cover layer 65 so that thecover layer 60 is sufficiently durable and wear resistant. The substrate65 may be made of any plastic or polymer suitable for use in an airbagmodule cover application. In an exemplary embodiment, the substrate 65is formed of polycarbonate/ABS. As shown in FIGS. 1 and 3A-3C, thesurface layer 70 is disposed on the substrate 65 and forms an outer (ortop) layer of the lid 44. As a result, the surface layer 70 dictates theappearance of the cover layer 60. The surface layer 70 may be made ofleather, a synthetic material (e.g., plastic), or a metallic material(e.g., aluminum, copper, brass, stainless steel, chrome, etc.). In anexemplary embodiment, surface layer 70 is made of aluminum.Additionally, the feel of the cover layer 60 may be customized based onthe particular stylistic theme of the vehicle. For example, the coverlayer 60 may be rigid so that the cover layer 60 is substantiallyimpervious to deformation. Alternatively, the cover layer 60 may includecushioning so that the cover layer 60 has a pliable feel.

The surface layer 70 is configured to be disposed on the substrate 65 sothat the surface layer 70 substantially covers a front surface 64 and aside surface 66 of the substrate 65 as shown in FIGS. 3A and 3B. Thesurface layer 70 may also cover a rear surface 68 of the substrate 65.In an exemplary embodiment (shown in FIG. 3A), the surface layer 70 isformed as a sheet, and the substrate 65 is formed as a panel. As shownin FIGS. 3A-3C, the surface layer 70 is attached to the substrate 65 byplacing the surface layer 70 on the substrate 65 and folding (orwrapping) edges 73 of the surface layer 70 over and around edges 63 ofthe substrate 65. After the folding operation, the edges 73 of thesurface layer 70 may be secured to the substrate 65 by crimping theedges 73 of the surface layer 70 to the rear surface 68 of the substrate65. The surface layer 70 may also be secured to the substrate 65 bytacking, adhesive, and/or standard attachment hardware so that thesurface layer 70 remains fixed to the substrate 65. According to analternative embodiment, the surface layer 70 may be formed by sputteringa metallic material (e.g., chrome) onto the substrate 65.

According to an embodiment, the cover layer 60 may be formed as a singleportion, as shown in FIG. 8. For example, the substrate 65 may be aone-piece panel, and the surface layer 70 may be a decal configured toadhere to the substrate 65. In this embodiment, the substrate 65 and thesurface layer 70 each have a thickness that is sufficiently thin toenable the airbag 10 to deploy through the cover layer 60. As a result,a pre-weakened tear line does not need to be formed in the cover layer60. Thus, the manufacturing process is simplified because a pre-weakenedportion (i.e., groove 52) needs to be formed only on the base layer 50.

According to another embodiment, the cover layer 60 may include multipleportions as shown in FIG. 2. For example, the cover layer 60 may includea first portion 60 a and a second portion 60 b. Each of the first andsecond portions 60 a and 60 b includes a substrate 65 and a cover layer70 substantially as described above. In this embodiment, the cover layer60 is attached to the base layer 50 so that the first portion 60 a isdisposed on one side of the groove 52. The second portion 60 b isdisposed adjacent to the first portion 60 a but is located on anopposite side of the groove 52. As shown in FIG. 5, relative to thevehicle instrument panel 200, the first portion 60 a may be locatedabove the groove 52 to form a first door (or panel), and the secondportion 60 b may be located below the groove 52 to form a second door(or panel).

In this embodiment, because the first and second portions 60 a and 60 bare disposed adjacent to one another but on opposite sides of the groove52, the first and second portions 60 a and 60 b of the cover layer 60separate (or move apart) from one another when the base layer 50ruptures at the groove 52. Thus, the cover layer 60 is not required torupture in order for the airbag 10 to deploy. As a result, a widevariety of materials may be used to form the cover layer 60. Forexample, metals and other materials considered to be non-compliant forairbag applications may be used to form the cover layer 60. The expandedrange of materials allows the design of various patterns that enhancethe look and feel of the cover layer 60 for so that the cover layer 60may be customized for a desired styling themes (e.g., leather wraps,patterns, graphic emblem designs, embossed metal, paint, etc.).Additionally, the cover layer 60 does not require additional processingto form a pre-weakened portion to facilitate airbag deployment.

According to an embodiment, a method of forming the module cover 40 forthe airbag module 100 includes providing a base layer 50 having a groove(or pre-weakened portion) 52 for deploying the airbag 10, providing asubstrate 65 including a first portion (or panel) and a second portion(or panel), providing a surface layer 70 including a first metal sheetand a second metal sheet, wrapping the first metal sheet around thefirst panel so that the first metal sheet substantially covers front andside surfaces of the first panel, wrapping the second metal sheet aroundthe second panel so that the second metal sheet substantially coversfront and side surfaces of the second panel, and attaching the first andsecond panels to the base layer.

Although the airbag module 100 shown in FIG. 1 is an airbag module for apassenger airbag device, the present invention is not limited topassenger airbag devices. Rather, the invention applies to any airbagdevice having an airbag module cover that is visible from a passengercompartment of a vehicle, including driver airbag devices, head/sidecurtain airbag devices, and side impact airbag devices.

Thus, according to embodiments of the present invention, an airbagmodule cover having an outer surface that forms part of a vehicleinstrument panel is provided. The outer surface may be formed form avariety of materials not typically used in airbag module applicationsand enables the airbag module cover to have an appearance and feel thatcan not be achieved with conventional module covers.

Given the disclosure of the present invention, one versed in the artwould appreciate that there may be other embodiments and modificationswithin the scope and spirit of the invention. Accordingly, allmodifications attainable by one versed in the art from the presentdisclosure within the scope and spirit of the present invention are tobe included as further embodiments of the present invention. The scopeof the present invention is to be defined as set forth in the followingclaims.

1. A cover for an airbag module including at least a first layer, a second layer, and a third layer, wherein the first layer includes a predefined tear line and the third layer is configured to face into a passenger compartment of a vehicle.
 2. The cover of claim 1, wherein the third layer forms part of a vehicle instrument panel.
 3. The cover of claim 1, wherein the third layer is made of a metallic material.
 4. The cover of claim 3, wherein the metallic material includes aluminum.
 5. The cover of claim 3, wherein the metallic material is embossed.
 6. The cover of claim 1, wherein the third layer includes a decal. 7.-12. (canceled)
 13. The cover of claim 1, wherein the second layer is formed of polycarbonate/ABS.
 14. The cover of claim 1, wherein only the first layer includes a predefined tear line for deploying an airbag.
 15. The cover of claim 1, wherein the first layer is formed of thermoplastic olefin.
 16. The cover of claim 1, wherein the second layer is disposed on the first layer.
 17. The cover of claim 16, wherein the second layer includes a plurality of bosses configured to be inserted into corresponding apertures in the first layer and deformed to retain the second on the first layer.
 18. The cover of claim 17, wherein the bosses are made of plastic and are configured to be deformed by melting.
 19. The cover of claim 16, wherein the second layer includes tabs for connecting the second layer to the first layer.
 20. The cover of claim 19, wherein the second layer includes a bracket and the tabs project from the bracket.
 21. The cover of claim 20, wherein the bracket is disposed within a recess in the second layer.
 22. The cover of claim 20, wherein the bracket is molded into the second layer. 23.-31. (canceled)
 32. An airbag module configured to be positioned in a vehicle so that a cover of the module forms a portion of the vehicle instrument panel and wherein the cover includes a metal top layer configured to separate into at least two pieces to allow an airbag to deploy therethrough. 33.-39. (canceled) 